Testing Tight Gas and Unconventional Formations and Determination of Closure Pressure

Soliman, Mohamed Y.; Gamadi, Talal

doi:10.2118/150948-ms

Cited by 12 publications

(2 citation statements)

References 10 publications

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“…Usually, they will slide easier than open, the shear mechanical limit will be discussed thereafter. The shearing force acted on natural fracture can be calculated as follows [21].…”

Section: Shearing Of Natural Fracturesmentioning

confidence: 99%

Study of Cyclic Fracturing in Vertical CBM Wells

Li¹,

Wan²

2017

TOPEJ

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Background:Coal-bed methane productivity of single well is very low, and has been the bottleneck of the coal-bed methane industry in China. Objective:Although hydraulic fracturing is the only stimulation measure to develop CBM, it cannot increase production effectively, conventional fracturing method to create opening fractures should be improved. How to make good use of natural fractures, which are plentiful in CBM reservoirs, is also an important subject for hydraulic fracturing. Method:In this paper, the plastic deformation of coal rock is analyzed by harnessing a pseudo-Maxwell creep phenomenon, which is normally present in rock. The Kelvin-Voigt model is utilized to describe pseudo-plastic behavior of coal rock to determine pressurization and decay cyclic time for cyclic fracturing design. The mechanical requirement for shearing natural fractures is also analyzed, and shearing distance between the faces of natural fracture can be calculated by Westergaard stress function. Ultimately, the cyclic fracturing method is proposed according to theories about stress alteration and shearing of natural fractures. This method includes such periods as fracturing, pumping shut-down and so on. Conclusion:A complex fracture system can be created, which consists of opened and sheared fractures, then, large SRV(stimulated reservoir volume)and flowing drainage area can be acquired. In comparison with conventional fracturing method, this new way can make full use of the characteristics of CBM reservoirs and is more suitable to CBM. This method will lead to a significant increase of CBM production, and will achieve huge economic benefits.

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“…Usually, they will slide easier than open, the shear mechanical limit will be discussed thereafter. The shearing force acted on natural fracture can be calculated as follows [21].…”

Section: Shearing Of Natural Fracturesmentioning

confidence: 99%

Study of Cyclic Fracturing in Vertical CBM Wells

Li¹,

Wan²

2017

TOPEJ

View full text Add to dashboard Cite

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“…These interpretations of non-ideal transients were developed based on published work by Barree and Mukherjee (1996) and Barree et al (2007) and are widely used in DFIT interpretation (Soliman and Kabir, 2012;Soliman and Gamadi, 2012;Cramer and Nguyen, 2013;Padmakar, 2013;Wallace et al, 2014;Meng et al, 2014;Barree et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Re-examining interpretations of non-ideal behavior during diagnostic fracture injection tests

Jung

Sharma

Cramer

et al. 2016

Journal of Petroleum Science and Engineering

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Re-examining interpretations of non-ideal behavior during diagnostic fracture injection tests, Journal of Petroleum Science and Engineering, http://dx. AbstractDiagnostic fracture injection tests (DFITs) are performed in low permeability formations to estimate the minimum principal stress, formation pressure, permeability, and other parameters. G-function derivative plots are used for diagnosing fracture closure and "non-ideal" reservoir processes. In this study, we use a discrete fracture network hydraulic fracturing simulator to investigate non-ideal DFIT mechanisms. The simulator fully couples fluid flow with the stresses induced by fracture deformation. DFITs are simulated for six different scenarios: a single hydraulic fracture, multiple fracture strands, opening of transverse fractures, near-wellbore complexity, far-field complexity, and height recession. The results indicate that pressure transient behavior commonly ascribed to "fracture height recession," "closure of transverse fractures," and "fracture tip extension" are likely to be misinterpreted by conventional techniques. In previous studies, we found that a curving upward G×dP/dG plot is caused by changing fracture stiffness after closure and that the closure pressure is best picked when G×dP/dG begins to deviate upward. In contrast, the commonly used "tangent" method can significantly underestimate the minimum principal stress. The results of this study confirm those prior results. The results suggest that in most cases, it should be possible to use pump-in/flowback tests to confirm estimates of the minimum principal stress. However, if a flow bottleneck occurs at the wellbore due to near-wellbore complexity, the pump-in/flowback test may be uninterpretable.

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Interpretation of Closure Stress in the Montney Shale Using PTA Based Techniques

Bachman

Anderson

Hawkes³

et al. 2013

Day 1 Mon, February 04, 2013

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The Montney formation In NE British Columbia and NW Alberta is one of the largest economically feasible resource plays in North America. It contains both gas and liquids rich light ends. Horizontal multi-staged fracturing is the method for developing this vast resource. Prior to hydraulically fracturing the wellbore, the toe stage is frequently mini-fraced to obtain reservoir and geomechanical properties. Interpreting these mini-fracs, commonly referred to as DFIT’s (Diagnostic Fracture Injection Tests), has proved to be a challenge using traditional combination G Function and square root plots. It is always important to ensure that all data being analyzed is associated with a reservoir response and not wellbore behavior, surface operational interruptions or data quality issues. Some of these challenges can be overcome when using some new techniques for mini-frac Fall-off analysis, which will be discussed in this paper. Various pressure transient analyses (PTA) based interpretation techniques have been introduced to the industry over the last couple of years for the determination of closure pressure (Bachman et al. 2012, Mohamed et al. 2011 and Marongiu-Porcu et al. 2011). From a theoretical viewpoint, unification of the fields of traditional PTA and mini-frac interpretation has been achieved. We recommend that the standard PTA based log-log derivative plot using equivalent time is included in the analysis of mini-frac / fall-off tests. This plot is rarely, if ever, used in current interpretations. For mini-frac interpretation, the starting point should now be the standard PTA based log-log derivative plot. The primary pressure derivative (dp/dt) curve should also be added to the log-log derivative plot as an independent flow regime identification technique. This now gives two independent flow regime identification techniques in one plot. The power of the primary pressure derivative to enhance the interpretation of closure and flow regime identification will be illustrated. Subsequently, flow regime specific plots can be constructed to enhance the interpretation. A number of field examples from the Montney formation in the Farrell Creek area of NE British Columbia are illustrated using a systematic PTA interpretation methodology demonstrating multiple closure events, high fracture extension pressure gradients of 34.0 kPa/m, non-Darcy pressure derivative diagnostics and observation of complex fracture orientation.

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Testing Tight Gas and Unconventional Formations and Determination of Closure Pressure

Cited by 12 publications

References 10 publications

Study of Cyclic Fracturing in Vertical CBM Wells

Study of Cyclic Fracturing in Vertical CBM Wells

Re-examining interpretations of non-ideal behavior during diagnostic fracture injection tests

Interpretation of Closure Stress in the Montney Shale Using PTA Based Techniques

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